In the construction of concrete structures and, in particular, in the construction of concrete wall panels it is well known in the art that it is desirable to provide a chamfer adjacent all edges of the concrete casting so that the structure will not require further finishing and so that the edges will be sufficiently strong and not easily broken by accidental impact.
In the formation of concrete wall panels one method which has been successfully employed is that of forming the concrete wall panels on their sides atop a suitable support structure. In setting up the form used to retain the poured concrete, one method which has been employed is quite time-consuming and wasteful of materials. In this previously employed method, the perimeter of the wall to be formed is marked out on a suitable support structure, e.g., a concrete slab. Holes are then drilled a predetermined distance from each other along the marked perimeter. Then, the lumber forms which are to be used in retaining the concrete are aligned adjacent the marked perimeter. Marks are made on the lumber which correspond to the holes drilled along the perimeter. Next, holes are drilled in the lumber at each marked location. Long nails or the like are then placed in the upright holes made in the concrete slab and the forms are then placed upon and retained in position by the nails. At each corner of the form, the lumber forms are mitered and nailed at a right angles to each other.
Once the lumber forms have been set in place, wooden chamfer strips are nailed to the inside perimeter of the lumber forms both at the top and bottom edges. By affixing these chamfer strips to the forms, the formed concrete wall will have all edges chamferred.
The above-described method of forming wall panels utilizes a wooden lumber form and wooden triangular shaped chamfer strips which are attached together prior to the casting of the concrete structure. Other types of chamfer strips have been disclosed in the art. For example, U.S. Pat. No. 2,940,152 discloses a chamfer strip which has an edge that may be attached to a mold. The chamfer strip disclosed in that patent must be nailed or otherwise affixed to the form and that strip is not adapted to receive and support the form.
U.S. Pat. No. 2,718,685 discloses a chamfer strip which is arranged as a frame mountable in a form to provide chamferring at the top of the casting. The device is described in that patent as being one which is adapted to receive and secure a chamfer strip or which is used in those instances where a chamfer strip had already been placed in the form.
U.S. Pat. No. 2,991,532 discloses a chamfer strip which includes two members. One member is a bracket which is detachably secured to a form and the other member is a concrete molding surface which can be attached to the secured bracket. In that patent it is disclosed that the concrete molding form can be of any suitable configuration and either member of the chamfer strip can be of sheet metal or of a molded or extruded synthetic material such as methyl methacrylate.
U.S. Pat. No. 3,782,680 discloses a chamfer strip which may be used for locating a concrete form used in the construction of monolithic slab and beam construction. The chamfer strip disclosed in that patent is utilized in concrete construction where a U-shaped pan is employed to form a void area in the concrete. The chamfer strip is described as having a flat base portion, a chamfer portion extending angularly upwardly from the base portion at one end thereof, and a ridge portion extending upwardly from the base portion and spaced from the chamfer portion, wherein the base portion extends beyond the ridge portion to provide an attachment means for securement of the chamfer strip to a support structure. It is further disclosed that the chamfer strip may be formed integrally of a plastic material from the group consisiting of acrylonitrilebutadiene-styrene, polystyrene, polyethylene and polyurethane. The ridge portion and the chamfer portion are disclosed as being spaced so that a longitudinal groove is formed for receiving the upright edge of the form.
The devices and methods which were utilized in the prior art have many disadvantages. Some of the prior art devices appear to be expensive to manufacture. Others, while apparently inexpensively manufactured are disadvantageous in that they are not easily placed into proper position. Because of this, labor costs are significantly increased when those devices are used. Another disadvantage is that no device has been provided which is adapted to receive and support a nominally sized two inch form of lumber. Furthermore, no provision has been made in the prior art from casting multiple concrete structures while simultaneously using the same chamfer device.